1. Field of the Invention
The present invention relates to orthopaedic reamer handles, and, more particularly, to orthopaedic reamer handles with an offset.
2. Description of the Related Art
A hip replacement surgery is a common orthopaedic procedure that is performed when a patient's cartilage in the acetabulum joint of the hip has been damaged or destroyed, leading to bone-on-bone contact between the femoral head and the hip. The bone-on-bone contact leads to the formation of arthritic bone and cartilage, which must be removed prior to inserting the hip implant. To remove arthritic bone and cartilage, as well as create a good contact surface for installation of an acetabular cup, an acetabular reamer is used. Most acetabular reamers have a reamer head with a spherical shape and openings formed throughout the surface of the reamer head, much like a cheese grater. The reamer head is connected to a rotary driver, such as a drill, by a drive train within the reamer, and removes the diseased bone and cartilage as it spins within the acetabulum. Orthopaedic reamers are also used in other joints of the body, such as the glenohumeral joint.
In some acetabular reamer designs, the section of the reamer containing the drive train, referred to as a reamer handle, has an offset between the part that connects to the driver and the reamer head. The offset of the reamer handle allows for the reamer head to access the acetabulum on a different axis than the driver, which can be beneficial during surgery. An offset reamer handle requires a substantially different drive train than a straight reamer handle to transfer rotational torques from the driver to the reamer head, as well as a different casing to enclose the drive train.
One such reamer handle is described in U.S. Pat. No. 8,480,674 to Roger et al. The reamer handle described in Roger et al. has a driver portion connected to a driver, a shaft rotatably connected to the driver portion, and a joint between the shaft and a reamer head that transfers torque from the shaft to the reamer head. The joint is angled relative to the shaft to provide the offset for the reamer handle. One limitation of the reamer handle described in Roger et al. is that the length and angle of the offset is determined by the joint, lowering the design flexibility of the reamer handle. The joint connecting the shaft to the reamer head of Roger et al. also has pins that rigidly connect the shaft and reamer head to the joint, i.e., the pins don't rotate during operation, and bear little of the frictional forces that produce wear during operation.
What is needed in the art is an offset orthopaedic reamer handle that allows for more design flexibility and has better wear distribution.